Method of polymerizing rosin and rosin esters



atented Aug. 17, 1943 UNITED STATES PATENT OFFICE METHOD OF POLYMERIZINGBOSIN AND ROSIN ESTERS Joseph N. Borglin, Wilmington, per, assignor toHercules Powder Company, Wilmington, Del, a

corporation of Delaware No Drawing. Application April 23, 1941,

' Serial No. 389,893

, particular polymerization catalyst employed. It

has been observed that a discoloration accompanies the polymerizationreaction and that the polymerized products obtained usually have adarker color than the original material. For this reason, it has beennecessary to subject the polymerized products to a refining treatment toimprove the color thereof. Such refiningprocedures have not been verysatisfactory due to the fact that they do not satisfactorily improve thecolor and particularly because they have a I tendency to decrease themelting point of the polymerized product, thereby defeating the orig-.inal purpose of the polymerization treatment.

Also, a material decrease in yield accompanies the known refiningprocedures.

It is an object of this invention to provide an improved method ofpolymerizing rosin and rosin esters.

It is another object to provide a method of producing p lymerized rosinand rosin esters of lighter color.

Other objects of the invention will appear hereinatter.

It has been found in accordance with this invention that much of thediscoloration accompanying the polymerization of rosin and rosinesterscan be avoided by carrying out the polymerization reaction in thepresence of a nonoxidizing atmosphere. This discovery was verysurprising and unexpected in view of the fact that rosins and rosinesters themselves do not ordinarily undergo color degradation in thepres ence of oxygen at the temperatures used in the polymerizationprocesses. Thus, it would not be expected that elimination of oxygen inthe polymerization treatment would provide a polymerized product ofimproved color. Accordingly, in accordance with this invention thepolymerization of rosin and rosin esters is carried out by contactingsuch materials with a polymerization catalyst in the presence of aninert gas.

The polymerization according to this invention may be carried out on anyof the various grades of wood or gum rosin or acids contained thereinwith use of any of the known catalysts such as for example, sulfuricacid, organic substituted sulfuric acids, phosphoric acid,tetraphosphoric' acid, boron trifiuoride and its organic complexes,metallic halides as stanm'c chloride, zinc chloride, aluminum chloride,hydrofluoric acid or the acid sludge formed by treatment of rosin withsulfuric acid such as is described in an application of Clell E. Tyler,Serial No. 328,864, filed April 10, 1940. By use of these catalystspolymerized rosins ranging in melting point from about 85 to 175C. maybe prepared. In a similar manner, rosin esters, either monohydric orpolyhydric alcohol esters, may be used in the improved polymerizationprocess. Thus esters such as the methyl, ethyl, propyl, butyl, ethyleneglycol, propylene glycol, glycerol, pentaerythritol, etc. esters of thevarious rosins and rosin acids may be employed.

The polymerization will generally be ca ried out on the rosin or rosinester dissolved an inert organic solvent. Suitable inert solvents arethe saturated petroleum hydrocarbons as butane, petroleum ether,gasoline, hexane, etc.; aromatic hydrocarbons as benzene, toluene,xylene; cyclic hydrocarbons as cyclohexane, paramenthane,tetrahydronaphthalene, decahydronaphthalene;

and chlorinated solvents as ethylene dichloride,

etc. The most preferable solvents are the saturated petroleumhydrocarbons and the aromatic hydrocarbons.

In carrying out the polymerization in accordance with the improvedmethod of this invention, the rosin or rosin ester dissolved in asuitable inert organic solvent is treated with a polymerlzation catalystfor a length of time sufiicient to provide the desired increaseinmelting point in the presence of an inert atmosphere such as will beprovided by passing a stream :of an inert gas such as nitrogen, carbondioxide, hydrogen, flue gas, etc., into the polymerization mixture.Preferably, the rosin or rosin ester solution prior to contacting withthe polymerization catalyst will be saturated with the inert gas bybubbling the latter through the solution. After the polymerization, thecatalyst will be removed by any of the well known means such as bydecantation of the catalyst sludge as in the case of sulfuric acid,followed by water-washing, or by waterwashing alone. The washing stepwill be carried out.in an atmosphere of the inert gas. After completeremoval of the catalyst the inert organic solvent is removed, forexample by distillation and the distillation is carried out in anatmosphere of the inert gas. Thus, the polymerized product obtained ispolymerized and purified in the presence of an inert atmosphere providedby an inert gas such as the gases mentioned above. 7

The improved polymerized product will be characterized by having alighter color than is obtainable by carrying out the polymerizationwithout use of the inert gas. Thus, it has been found that with any ofthe catalysts and with any of the polymerization processes a color im:-provement of the polymerized product is obtainable in each instance bycarrying out the treatment in the presence of an inert gas. The othercharacteristics of the polymerized product will be substantiallyunaltered. Thus the process defined in accordancewith this inventionmakes it possible to provide polymerized rosins and rosin esters oflighter color than heretofore obtainable without special refiningtreatment.

The following examples are illustrative of the improved method ofpolymerization. In the examples the amounts of ingredients are expressedin parts by weight unless otherwise indicated.

Example 1 Into 800 parts of a 35% solution of K wood rosin in benzene arapid stream of carbon dioxide was passed at a temperature of 15 C.Seventy-four parts of 95% sulfuric acid were then added gradually withagitation to the rosin solution maintaining the temperature at 15 C.and. the agitation continued for 30 minutes. A stream of carbon dioxidewas passed through the polymerization mixture during the agitation. Thesludge was then separated from the polymerized rosin solution and thelatter refluxed for 1 hour with 90 parts of water while passing a streamof carbon dioxide through the solution. The benzene solution was thenwashed substantially free of acid in an atmosphere of carbon dioxide.The polymerized rosin was then recovered by distilling off the solventby heatin to a temperature of 220 C. under 15 to 20 mm. pressure whilepassing a stream of carbon dioxide into the solution. The polymerizedrosin obtained had a melting point of 106 C., an acid number of 164, anda color of N+ on the rosin scale. By carrying out the polymerization inthe same manner but without use of the carbon dioxide atmosphere thepolymerized rosin obtained had a color of K. g

. Example 2 The polymerization procedure of Example 1 was duplicatedexcept with use of cyclohexane in place of benzene as the solvent. Thepolymerized rosin obtained had a melting point of 87 C. and a color of14 Amber on the Lovibond scale. A similar polymerization carried outwithout use of carbon dioxide atmosphere provided a polymerized rosinhaving a color of 27 Amber..

Example 3 between 30 and 32 C. by cooling. The rate of addition was suchas to be completed within a half hour. Stirring was continued for oneand one-half hours longer while continually passing a stream of carbondioxide through the solution. The mixture was then stirred into 2000 cc.of gasoline saturated with carbon dioxide. Separation into a gasolinelayer and an acid layer took place. The gasoline layer was washed withwater in an atmosphere of carbon dioxide to remove any free or combinedacid. The solution was then distilled at 15 to 20 mm. pressure to removethe gasoline, heating to a temperature of 220 C. The resultingpolymerized rosin had a drop melting point of 120 C. and a color of WW.A similar preparation without use of an inert atmosphere gave apolymerized rosin having a color of K+.

Example 4 A solution of 200 parts of K wood rosin in 400 parts ofbenzene was saturated with carbon dioxide at room temperature and 20parts of a boron trifluoride-ether complex were added with shaking atroom temperature. After allowing the solution to stand at roomtemperature for 16 hours in an atmosphere of carbon dioxide, it waswashed free of catalyst in a carbon dioxide' atmosphere and the benzeneremoved by heating the solution to a temperature of 220 C. under 15 to20 mm. pressure while passing a stream of carbon vdioxide through thesolution. The polymerized rosin obtained had an acid number of 166, amelting point of 103 C. and a color of '80 Example 5 A solution of 200parts of K wood rosin in 300 parts of ethylene dichloride was saturatedby passing nitrogen through the solution. Twenty parts of anhydrousaluminum chloride dissolved in 72 parts of ethylene dichloride which hadbeen previously saturated with nitrogen were then added to the rosinsolution at room temperature in a nitrogen atmosphere. The solution wasallowed to stand for 72 hours at a temperature of approximately 0 C. ina nitrogen atmosphere. The solution was then washed with 1000 parts of15% hydrochloric acid solution, followed by washing with water until thewash water was neutral, the washing being carried out in an atmosphereof nitrogen. The polymerized rosin was'then recovered by heating thesolution to a temperature of 220 C. under 15 to 20 mm. pressure whilepassing a stream of nitrogen through the solution. The polymerized rosinobtained had an acid number of 167, a melting point of 98 C. and a colorof Amber+6 Red on the Lovibond scale. In a comparable polymerizationcarried out without the use of nitrogen the polymerized rosin obtainedhad a color of 80 Amber+55 Red.

Example 6 A solution of 240 parts of ester gum in 160 parts of narrowrange gasoline having a boiling range of to C. was heated to the refluxtemperature while passing af'rapid stream of carbon dioxide through thesolution. The solution was then cooled to 30 C. and 240 parts of 80%sulfuric acid added. The mixture was stirred for 1 /2 hours at the sametemperature while passing a stream of carbon dioxide through thesolution. The polymerization mixture was then diluted with 330 parts ofadditional gasoline and the polymerized rosin solution then separatedfrom the sludge. The solution was then refluxed for 1 hour with 200parts of sulfuric acid solution in an atmosphere of carbon dioxide. Thesolution was then washed free of acid in a carbon dioxide atmosphere andthe solvent removed by heating to a temperature of 220 C. under to mm.pressure while passing a stream of carbon dioxide into the solution. Thepolymerized ester gum obtained had a melting point of 123 C. and a colorof Amber on the Lovibond scale. A comparable polymerization carried outwithout the use of the carbon dioxide provided an ester gum having acolor of 59 Amber.

The improved polymerized rosins' and rosin esters obtained in accordancewith the process of this invention may be subjected to any furthertreatment desired. Thus, for example, they may be subjected to refiningtreatmentsif it is desired to further improve the color. Thus, theproducts may be refined by means of selective solvents or adsorbents.

It will be understood that the detail and examples hereinbefore setforth are illustrative only and that the invention as broadly describedand claimed is in no way limited thereby.

What I claim and desire to protect by Letters Patent is:

1. A method for polymerizing a material selected from the groupconsisting of rosins and rosin esters, which comprises dissolving thesaid material in an inert organic solvent, saturating the solution withan inert gas, contacting said solution with a polymerization catalyst inan inert atmosphere to effect polymerization of the said material,removing the catalyst in an inert atmosphere, washing the said solutionwith water in an inert atmosphere to remove th catalyst, evaporating thesolvent in an inert atmosphere, and recovering a polymerized material ofimproved color.

2. A method for polymerizing a rosin which comprises dissolving therosin in an inert organic solvent, saturating the solution with an inertgas, contacting said solution with a polymerization catalyst in an inertatmospher to efiect polymerization of the said rosin, removing the cataolyst in an inert atmosphere, washing the said solution with water in aninert atmosphere to remove the catalyst, evaporating the solvent in aninert atmosphere, and recovering a polymerized rosin of improved color.

.3. A method for polymerizing a rosin ester which comprises dissolvingthe rosin ester in an inert organic solvent, saturating the solutionwith an inert gas, contacting said solution with a polymerizationcatalyst in an inert atmosphere to eflect polymerization of the saidrosin ester, removing the catalyst in an inert atmosphere, washing thesaid solution with water in an inert atmosphere to remove the catalyst,evaporating the solvent in an inert atmosphere, and recovering apolymerized rosin ester of improved color.

4. A method for polymerizing a rosin which comprises dissolving therosin in an inert organic solvent, saturating the solution with an inertgas,

contacting the solution with a sulfuric acid catalyst in an inertatmosphere to effect polymerization of the rosin, removing the catalystin an inert atmosphere, washing the solution with water in an inertatmosphere to remove the catalyst, evaporatingthe solvent inan inertatmosphere, and recovering a polymerized rosin of improved color.

5. A method for polymerizing a rosin which comprises dissolving therosin in an inert organic solvent, saturating the solution with an inertgas, contacting the solution with a boron fluoride catalyst in an inertatmosphere to effect polymerization of the rosin, removing the catalystin an inert atmosphere, washing the solution with water in an inertatmosphere to remove the catalyst, evaporating the solvent in an inertatmosphere and recovering a polymerized rosin of improved color.

6. A method for polymerizing a rosin which comprises dissolving therosin in an inert organic solvent, saturating the solution with an inertgas, contacting the solution with an aluminum chloride catalyst in aninert atmosphere to effect polymerization of the rosin, removing thecatalyst in an inert atmosphere, washing the solution with water in aninert atmosphere to remove the catalyst, evaporating the solvent in aninert atmosphere and recovering (a polymerized rosin of improved color.

JOSEPH N. BORGHN.

